This page was generated from
ex-gwt-mt3dms-p08.py.
It's also available as a notebook.
MT3DMS Problem 8
The purpose of this script is to (1) recreate the example problems that were first described in the 1999 MT3DMS report, and (2) compare MF6-GWT solutions to the established MT3DMS solutions.
Ten example problems appear in the 1999 MT3DMS manual, starting on page 130. This notebook demonstrates example 8 from the list below:
One-Dimensional Transport in a Uniform Flow Field
One-Dimensional Transport with Nonlinear or Nonequilibrium Sorption
Two-Dimensional Transport in a Uniform Flow Field
Two-Dimensional Transport in a Diagonal Flow Field
Two-Dimensional Transport in a Radial Flow Field
Concentration at an Injection/Extraction Well
Three-Dimensional Transport in a Uniform Flow Field
Two-Dimensional, Vertical Transport in a Heterogeneous Aquifer
Two-Dimensional Application Example
Three-Dimensional Field Case Study
Initial setup
Import dependencies, define the example name and workspace, and read settings from environment variables.
[1]:
import os
import pathlib as pl
from pprint import pformat
import flopy
import git
import matplotlib.pyplot as plt
import numpy as np
import pooch
from flopy.plot.styles import styles
from flopy.utils.util_array import read1d
from modflow_devtools.misc import get_env, timed
# Example name and workspace paths. If this example is running
# in the git repository, use the folder structure described in
# the README. Otherwise just use the current working directory.
sim_name = "ex-gwt-mt3dms-p08"
try:
root = pl.Path(git.Repo(".", search_parent_directories=True).working_dir)
except:
root = None
workspace = root / "examples" if root else pl.Path.cwd()
figs_path = root / "figures" if root else pl.Path.cwd()
data_path = pl.Path(f"../data/{sim_name}")
data_path = data_path if data_path.is_dir() else pl.Path.cwd()
# Settings from environment variables
write = get_env("WRITE", True)
run = get_env("RUN", True)
plot = get_env("PLOT", True)
plot_show = get_env("PLOT_SHOW", True)
plot_save = get_env("PLOT_SAVE", True)
Define parameters
Define model units, parameters and other settings.
[2]:
# Model units
length_units = "meters"
time_units = "days"
# Model parameters
nlay = 27 # Number of layers
nrow = 1 # Number of rows
ncol = 50 # Number of columns
delr = 5.0 # Column width ($m$)
delc = 1.0 # Row width ($m$)
delz = 0.25 # Layer thickness ($m$)
top = 6.75 # Top of the model ($m$)
prsity = 0.35 # Porosity
dm = 5.0e-4 # Horiz. hyd. conductivity of fine grain material ($cm/sec$)
dm = 1.0e-2 # Horiz. hyd. conductivity of medium grain material ($cm/sec$)
rech = 10.0 # Applied recharge rate ($cm/yr$)
al = 0.5 # Longitudinal dispersivity ($m$)
tral = 0.005 # Transverse vertical dispersivity ($m$)
dmcoef = 1.34e-5 # Effective diffusion coefficient ($cm^2/sec$)
perlen = 20.0 # Simulation time ($years$)
# Additional model input
k1 = 5e-4 / 100.0 * 86400 # m/d
k2 = 1e-2 / 100.0 * 86400 # m/d
k11 = k1 * np.ones((nlay, nrow, ncol), dtype=float)
k11[11:19, :, 0:24] = k2
k11[11:19, :, 36:] = k2
laytyp = 6 * [1] + 21 * [0]
# Setting starting head information
fname = "p08shead.dat"
fpath = pooch.retrieve(
url=f"https://github.com/MODFLOW-USGS/modflow6-examples/raw/master/data/{sim_name}/{fname}",
fname=fname,
path=data_path,
known_hash="md5:673d570ab9d496355470ac598c4b8b55",
)
f = open(fpath)
strt = np.empty((nlay * ncol), dtype=float)
strt = read1d(f, strt).reshape((nlay, nrow, ncol))
f.close()
# Active model domain
ibound = np.ones((nlay, nrow, ncol), dtype=int)
ibound[5:, :, -1] = -1
ibound[strt < 0] = 0
idomain = 1
# Fow boundary condition
rech = 10.0 / 100 / 365 # cm/yr -> m/d
# Transport relate`xd
trpt = 0.01 # Ratio of transverse to longitudinal dispersitivity
trpv = 0.01 # Ratio of vertical to longitudinal dispersitivity
dmcoef = 1.34e-5 / 100 / 100 * 86400 # cm^2/s -> m^2/d
ath1 = al * trpt
atv = al * trpv
# Time variables
perlen = [5 * 365, 15 * 365]
nper = len(perlen)
nstp = [365, 1095]
tsmult = [1.0, 1.0]
sconc = 0.0
c0 = 0.0
botm = [top - delz * k for k in range(1, nlay + 1)]
k33 = k11 # Vertical hydraulic conductivity ($m/d$)
icelltype = 6 * [1] + 21 * [0]
mixelm = -1
# Boundary conditions
# MF6 constant head boundaries:
chdspd = []
# Left side of model domain is no flow; right side uses constant heads
for k in np.arange(nlay):
if strt[k, 0, -1] != -999:
# (l, r, c), head, conc
chdspd.append([(k, 0, ncol - 1), strt[k, 0, -1], 0.0])
chdspd = {0: chdspd}
# SSM related input data
crch1 = np.zeros((nrow, ncol), dtype=float)
crch1[0, 9:18] = 1.0
cnc0 = [(0, 0, j, 1, -1) for j in range(8, 16)]
cnc1 = [(0, 0, j, 0.0, -1) for j in range(8, 16)]
ssmspd = {0: cnc0, 1: cnc1}
# Setup constant concentration information for MF6
cncspd_1 = []
cncspd_2 = []
cnc_1 = 1.0 # t <= 5 yrs
cnc_2 = 0.0 # t > 5 yrs
for col in np.arange(8, 16):
cncspd_1.append([(0, 0, col), cnc_1]) # t <= 5 yrs
cncspd_2.append([(0, 0, col), cnc_2]) # t > 5 yrs
cncspd = {0: cncspd_1, 1: cncspd_2}
# Solver settings
nouter, ninner = 100, 300
hclose, rclose, relax = 1e-6, 1e-6, 1.0
percel = 1.0 # HMOC parameters
itrack = 3
wd = 0.5
dceps = 1.0e-5
nplane = 0
npl = 0
nph = 10
npmin = 2
npmax = 20
dchmoc = 1.0e-3
nlsink = nplane
npsink = nph
# Time discretization
tdis_rc = []
tdis_rc.append((perlen, nstp, 1.0))
Downloading data from 'https://github.com/MODFLOW-USGS/modflow6-examples/raw/master/data/ex-gwt-mt3dms-p08/p08shead.dat' to file '/home/runner/work/modflow6-examples/modflow6-examples/modflow6-examples/.doc/_notebooks/p08shead.dat'.
Model setup
Define functions to build models, write input files, and run the simulation.
[3]:
def build_models(mixelm=0, silent=False):
print(f"Building mf2005 model...{sim_name}")
mt3d_ws = os.path.join(workspace, sim_name, "mt3d")
modelname_mf = "p08-mf"
# Instantiate the MODFLOW model
mf = flopy.modflow.Modflow(
modelname=modelname_mf, model_ws=mt3d_ws, exe_name="mf2005"
)
# Instantiate discretization package
# units: itmuni=4 (days), lenuni=2 (m)
flopy.modflow.ModflowDis(
mf,
nlay=nlay,
nrow=nrow,
ncol=ncol,
delr=delr,
delc=delc,
top=top,
botm=botm,
nper=nper,
nstp=nstp,
perlen=perlen,
itmuni=4,
lenuni=2,
steady=[False, False],
)
# Instantiate basic package
flopy.modflow.ModflowBas(mf, ibound=ibound, strt=strt)
# Instantiate layer property flow package
flopy.modflow.ModflowLpf(mf, hk=k11, vka=k11, laytyp=icelltype)
# Instantiate recharge package
flopy.modflow.ModflowRch(mf, rech=rech)
# Instantiate solver package
flopy.modflow.ModflowPcg(mf)
# Instantiate link mass transport package (for writing linker file)
flopy.modflow.ModflowLmt(mf)
# Transport
print(f"Building mt3d-usgs model...{sim_name}")
modelname_mt = "p08_mt"
mt = flopy.mt3d.Mt3dms(
modelname=modelname_mt,
model_ws=mt3d_ws,
exe_name="mt3dusgs",
modflowmodel=mf,
)
# Instantiate basic transport package
flopy.mt3d.Mt3dBtn(
mt,
icbund=1,
prsity=prsity,
sconc=sconc,
nper=nper,
perlen=perlen,
timprs=np.arange(1, 21) * 365,
dt0=5,
)
# Instatiate the advection package
flopy.mt3d.Mt3dAdv(
mt,
mixelm=mixelm,
dceps=dceps,
nplane=nplane,
npl=npl,
nph=nph,
npmin=npmin,
npmax=npmax,
nlsink=nlsink,
npsink=npsink,
percel=percel,
itrack=itrack,
wd=wd,
)
# Instantiate the dispersion package
flopy.mt3d.Mt3dDsp(mt, al=al, trpt=trpt, trpv=trpv, dmcoef=dmcoef)
# Instantiate the source/sink mixing package
flopy.mt3d.Mt3dSsm(mt, stress_period_data=ssmspd)
# Instantiate the GCG solver in MT3DMS
flopy.mt3d.Mt3dGcg(mt)
# MODFLOW 6
print(f"Building mf6gwt model...{sim_name}")
name = "p08_mf6"
gwfname = "gwf_" + name
sim_ws = os.path.join(workspace, sim_name)
sim = flopy.mf6.MFSimulation(sim_name=sim_name, sim_ws=sim_ws, exe_name="mf6")
# Instantiating MODFLOW 6 time discretization
tdis_rc = []
for i in range(nper):
tdis_rc.append((perlen[i], nstp[i], tsmult[i]))
flopy.mf6.ModflowTdis(sim, nper=nper, perioddata=tdis_rc, time_units=time_units)
# Instantiating MODFLOW 6 groundwater flow model
gwf = flopy.mf6.ModflowGwf(
sim,
modelname=gwfname,
save_flows=True,
model_nam_file=f"{gwfname}.nam",
)
# Instantiating MODFLOW 6 solver for flow model
imsgwf = flopy.mf6.ModflowIms(
sim,
print_option="summary",
complexity="complex",
outer_dvclose=hclose,
outer_maximum=nouter,
under_relaxation="dbd",
linear_acceleration="BICGSTAB",
under_relaxation_theta=0.7,
under_relaxation_kappa=0.08,
under_relaxation_gamma=0.05,
under_relaxation_momentum=0.0,
backtracking_number=20,
backtracking_tolerance=2.0,
backtracking_reduction_factor=0.2,
backtracking_residual_limit=5.0e-4,
inner_dvclose=hclose,
rcloserecord="0.0001 relative_rclose",
inner_maximum=ninner,
relaxation_factor=relax,
number_orthogonalizations=2,
preconditioner_levels=8,
preconditioner_drop_tolerance=0.001,
filename=f"{gwfname}.ims",
)
sim.register_ims_package(imsgwf, [gwf.name])
# Instantiating MODFLOW 6 discretization package
flopy.mf6.ModflowGwfdis(
gwf,
length_units=length_units,
nlay=nlay,
nrow=nrow,
ncol=ncol,
delr=delr,
delc=delc,
top=top,
botm=botm,
idomain=idomain,
filename=f"{gwfname}.dis",
)
# Instantiating MODFLOW 6 node-property flow package
flopy.mf6.ModflowGwfnpf(
gwf,
save_flows=False,
icelltype=icelltype,
k=k11,
k33=k11,
save_specific_discharge=True,
filename=f"{gwfname}.npf",
)
# Instantiate storage package
sto = flopy.mf6.ModflowGwfsto(gwf, ss=0, sy=0)
# Instantiating MODFLOW 6 initial conditions package for flow model
flopy.mf6.ModflowGwfic(gwf, strt=strt, filename=f"{gwfname}.ic")
# Instantiating MODFLOW 6 constant head package
flopy.mf6.ModflowGwfchd(
gwf,
maxbound=len(chdspd),
stress_period_data=chdspd,
save_flows=False,
auxiliary="CONCENTRATION",
pname="CHD-1",
filename=f"{gwfname}.chd",
)
# Instantiate recharge package
flopy.mf6.ModflowGwfrcha(
gwf,
print_flows=True,
recharge=rech,
pname="RCH-1",
filename=f"{gwfname}.rch",
)
# Instantiating MODFLOW 6 output control package for flow model
flopy.mf6.ModflowGwfoc(
gwf,
head_filerecord=f"{gwfname}.hds",
budget_filerecord=f"{gwfname}.bud",
headprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
saverecord=[("HEAD", "LAST"), ("BUDGET", "LAST")],
printrecord=[("HEAD", "LAST"), ("BUDGET", "LAST")],
)
# Instantiating MODFLOW 6 groundwater transport package
gwtname = "gwt_" + name
gwt = flopy.mf6.MFModel(
sim,
model_type="gwt6",
modelname=gwtname,
model_nam_file=f"{gwtname}.nam",
)
gwt.name_file.save_flows = True
# create iterative model solution and register the gwt model with it
imsgwt = flopy.mf6.ModflowIms(
sim,
print_option="summary",
complexity="complex",
outer_dvclose=hclose,
outer_maximum=nouter,
under_relaxation="dbd",
linear_acceleration="BICGSTAB",
under_relaxation_theta=0.7,
under_relaxation_kappa=0.08,
under_relaxation_gamma=0.05,
under_relaxation_momentum=0.0,
backtracking_number=20,
backtracking_tolerance=2.0,
backtracking_reduction_factor=0.2,
backtracking_residual_limit=5.0e-4,
inner_dvclose=hclose,
rcloserecord="0.0001 relative_rclose",
inner_maximum=ninner,
relaxation_factor=relax,
number_orthogonalizations=2,
preconditioner_levels=8,
preconditioner_drop_tolerance=0.001,
filename=f"{gwtname}.ims",
)
sim.register_ims_package(imsgwt, [gwt.name])
# Instantiating MODFLOW 6 transport discretization package
flopy.mf6.ModflowGwtdis(
gwt,
nlay=nlay,
nrow=nrow,
ncol=ncol,
delr=delr,
delc=delc,
top=top,
botm=botm,
idomain=idomain,
filename=f"{gwtname}.dis",
)
# Instantiating MODFLOW 6 transport initial concentrations
flopy.mf6.ModflowGwtic(gwt, strt=sconc, filename=f"{gwtname}.ic")
# Instantiating MODFLOW 6 transport advection package
if mixelm >= 0:
scheme = "UPSTREAM"
elif mixelm == -1:
scheme = "TVD"
else:
raise Exception()
flopy.mf6.ModflowGwtadv(gwt, scheme=scheme, filename=f"{gwtname}.adv")
# Instantiating MODFLOW 6 transport dispersion package
if al != 0:
flopy.mf6.ModflowGwtdsp(
gwt,
alh=al,
ath1=ath1,
atv=atv,
filename=f"{gwtname}.dsp",
)
# Instantiating MODFLOW 6 transport mass storage package
flopy.mf6.ModflowGwtmst(
gwt,
porosity=prsity,
first_order_decay=False,
decay=None,
decay_sorbed=None,
sorption=None,
bulk_density=None,
distcoef=None,
filename=f"{gwtname}.mst",
)
# Instantiating MODFLOW 6 transport source-sink mixing package
sourcerecarray = [("CHD-1", "AUX", "CONCENTRATION")]
flopy.mf6.ModflowGwtssm(gwt, sources=sourcerecarray, filename=f"{gwtname}.ssm")
# Instantiating MODFLOW 6 transport output control package
flopy.mf6.ModflowGwtoc(
gwt,
budget_filerecord=f"{gwtname}.cbc",
concentration_filerecord=f"{gwtname}.ucn",
concentrationprintrecord=[("COLUMNS", 10, "WIDTH", 15, "DIGITS", 6, "GENERAL")],
saverecord=[
("CONCENTRATION", "LAST"),
(
"CONCENTRATION",
"STEPS",
"73",
"146",
"219",
"292",
"365",
"438",
"511",
"584",
"657",
"730",
"803",
"876",
"949",
"1022",
"1095",
"1168",
"1241",
"1314",
"1387",
"1460",
),
("BUDGET", "LAST"),
],
printrecord=[("CONCENTRATION", "LAST"), ("BUDGET", "LAST")],
)
# Instantiate constant concentration at upper boundary.
flopy.mf6.ModflowGwtcnc(
gwt,
print_flows=True,
stress_period_data=cncspd,
pname="CNC-1",
filename=f"{gwtname}.cnc",
)
# Instantiating MODFLOW 6 flow-transport exchange mechanism
flopy.mf6.ModflowGwfgwt(
sim,
exgtype="GWF6-GWT6",
exgmnamea=gwfname,
exgmnameb=gwtname,
filename=f"{name}.gwfgwt",
)
return mf, mt, sim
def write_models(mf2k5, mt3d, sim, silent=True):
mf2k5.write_input()
mt3d.write_input()
sim.write_simulation(silent=silent)
@timed
def run_models(mf2k5, mt3d, sim, silent=True):
success, buff = mf2k5.run_model(silent=silent, report=True)
assert success, pformat(buff)
success, buff = mt3d.run_model(
silent=silent, normal_msg="Program completed", report=True
)
assert success, pformat(buff)
success, buff = sim.run_simulation(silent=silent, report=True)
assert success, pformat(buff)
Plotting results
Define functions to plot model results.
[4]:
# Figure properties
figure_size = (5, 7)
def plot_results(mf2k5, mt3d, mf6, idx, ax=None):
mt3d_out_path = mt3d.model_ws
mf6.simulation_data.mfpath.get_sim_path()
# Get the MT3DMS concentration output
fname_mt3d = os.path.join(mt3d_out_path, "MT3D001.UCN")
ucnobj_mt3d = flopy.utils.UcnFile(fname_mt3d)
conc_mt3d = ucnobj_mt3d.get_alldata()
# Get the MF6 concentration output
gwt = mf6.get_model(list(mf6.model_names)[1])
ucnobj_mf6 = gwt.output.concentration()
conc_mf6 = ucnobj_mf6.get_alldata()
# Create figure for scenario
with styles.USGSPlot():
plt.rcParams["lines.dashed_pattern"] = [5.0, 5.0]
hk = mf2k5.lpf.hk.array
# Which year to plot?:
yr_idx = [7, 11, 19] # 0-based
contourLevels = np.arange(0.05, 0.5, 0.05)
# Plot after 8 years
i = 0
axWasNone = False
if ax is None:
fig = plt.figure(figsize=figure_size, dpi=300, tight_layout=True)
ax = fig.add_subplot(2, 1, 1)
axWasNone = True
mx = flopy.plot.PlotCrossSection(ax=ax, model=mf2k5, line={"row": 0})
mx.plot_array(hk, masked_values=[hk[0, 0, 0]], alpha=0.2)
mx.plot_ibound()
mx.plot_grid(color="0.5", alpha=0.2)
cs = mx.contour_array(
conc_mt3d[yr_idx[i]], levels=contourLevels, masked_values=[1.0e30]
)
plt.clabel(cs, fmt=r"%4.2f")
title = "Migrating plume after " + str(yr_idx[i] + 1) + " years, MT3D-USGS"
letter = chr(ord("@") + idx + 1)
styles.heading(letter=letter, heading=title)
if axWasNone:
ax = fig.add_subplot(2, 1, 2)
mx = flopy.plot.PlotCrossSection(ax=ax, model=mf2k5, line={"row": 0})
mx.plot_array(hk, masked_values=[hk[0, 0, 0]], alpha=0.2)
mx.plot_ibound()
mx.plot_grid(color="0.5", alpha=0.2)
cs = mx.contour_array(
conc_mf6[yr_idx[i]], levels=contourLevels, masked_values=[1.0e30]
)
plt.clabel(cs, fmt=r"%4.2f")
title = "Migrating plume after " + str(yr_idx[i] + 1) + " years, MODFLOW 6"
letter = chr(ord("@") + idx + 2)
styles.heading(letter=letter, heading=title)
if plot_show:
plt.show()
if plot_save:
fpth = figs_path / "{}{}".format(
mf6.name + "-" + str(yr_idx[i] + 1) + "yrs",
".png",
)
fig.savefig(fpth)
# Plot after 12 years
i = 1
if axWasNone:
fig = plt.figure(figsize=figure_size, dpi=300, tight_layout=True)
ax = fig.add_subplot(2, 1, 1)
axWasNone = True
mx = flopy.plot.PlotCrossSection(ax=ax, model=mf2k5, line={"row": 0})
mx.plot_array(hk, masked_values=[hk[0, 0, 0]], alpha=0.2)
mx.plot_ibound()
mx.plot_grid(color="0.5", alpha=0.2)
cs = mx.contour_array(
conc_mt3d[yr_idx[i]], levels=contourLevels, masked_values=[1.0e30]
)
plt.clabel(cs, fmt=r"%4.2f")
title = "Migrating plume after " + str(yr_idx[i] + 1) + " years, MT3D-USGS"
letter = chr(ord("@") + idx + 3)
styles.heading(letter=letter, heading=title)
if axWasNone:
ax = fig.add_subplot(2, 1, 2)
mx = flopy.plot.PlotCrossSection(ax=ax, model=mf2k5, line={"row": 0})
mx.plot_array(hk, masked_values=[hk[0, 0, 0]], alpha=0.2)
mx.plot_ibound()
mx.plot_grid(color="0.5", alpha=0.2)
cs = mx.contour_array(
conc_mf6[yr_idx[i]], levels=contourLevels, masked_values=[1.0e30]
)
plt.clabel(cs, fmt=r"%4.2f")
title = "Migrating plume after " + str(yr_idx[i] + 1) + " years, MODFLOW 6"
letter = chr(ord("@") + idx + 4)
styles.heading(letter=letter, heading=title)
if plot_show:
plt.show()
if plot_save:
fpth = figs_path / "{}{}".format(
mf6.name + "-" + str(yr_idx[i] + 1) + "yrs",
".png",
)
fig.savefig(fpth)
# Plot after 20 years
i = 2
if axWasNone:
fig = plt.figure(figsize=figure_size, dpi=300, tight_layout=True)
ax = fig.add_subplot(2, 1, 1)
axWasNone = True
mx = flopy.plot.PlotCrossSection(ax=ax, model=mf2k5, line={"row": 0})
mx.plot_array(hk, masked_values=[hk[0, 0, 0]], alpha=0.2)
mx.plot_ibound()
mx.plot_grid(color="0.5", alpha=0.2)
cs = mx.contour_array(
conc_mt3d[yr_idx[i]], levels=contourLevels, masked_values=[1.0e30]
)
plt.clabel(cs, fmt=r"%4.2f")
title = "Migrating plume after " + str(yr_idx[i] + 1) + " years, MT3D-USGS"
letter = chr(ord("@") + idx + 5)
styles.heading(letter=letter, heading=title)
if axWasNone:
ax = fig.add_subplot(2, 1, 2)
mx = flopy.plot.PlotCrossSection(ax=ax, model=mf2k5, line={"row": 0})
mx.plot_array(hk, masked_values=[hk[0, 0, 0]], alpha=0.2)
mx.plot_ibound()
mx.plot_grid(color="0.5", alpha=0.2)
cs = mx.contour_array(
conc_mf6[yr_idx[i]], levels=contourLevels, masked_values=[1.0e30]
)
plt.clabel(cs, fmt=r"%4.2f")
title = "Migrating plume after " + str(yr_idx[i] + 1) + " years, MODFLOW 6"
letter = chr(ord("@") + idx + 6)
styles.heading(letter=letter, heading=title)
if plot_show:
plt.show()
if plot_save:
fpth = figs_path / "{}{}".format(
mf6.name + "-" + str(yr_idx[i] + 1) + "yrs",
".png",
)
fig.savefig(fpth)
Running the example
Define and invoke a function to run the example scenario, then plot results.
[5]:
def scenario(idx, silent=True):
mf2k5, mt3d, sim = build_models(mixelm=mixelm)
if write:
write_models(mf2k5, mt3d, sim, silent=silent)
if run:
run_models(mf2k5, mt3d, sim, silent=silent)
if plot:
plot_results(mf2k5, mt3d, sim, idx)
Compares the standard finite difference solutions between MT3D and MF6.
[6]:
scenario(0, silent=True)
Building mf2005 model...ex-gwt-mt3dms-p08
Building mt3d-usgs model...ex-gwt-mt3dms-p08
found 'rch' in modflow model, resetting crch to 0.0
Building mf6gwt model...ex-gwt-mt3dms-p08
<flopy.mf6.data.mfstructure.MFDataItemStructure object at 0x7f45116f99d0>
<flopy.mf6.data.mfstructure.MFDataItemStructure object at 0x7f45116f99d0>
run_models took 19631.59 ms
